lingenbrink



A ril 25, 1961 H. E. F. c. LINGENBRINK 2,981,114

DRIVE SYSTEM FOR TUNING ASSEMBLY Filed April 29. 1958 2 Sheets-Sheet 1 QINVENTOR.

L? FUPM H 770/? IVE) April 25, 1961 Filed April 29, 1958 H. E. F. C.LINGENBRINK DRIVE SYSTEM FOR TUNING ASSEMBLY 2 Sheets-Sheet 2 45" 42 44/6 i M? 1 fig 472} F3 F "W1 x W N I W9 M M NH W 11H 1/ T l\ T I 0 Z2 37! 37 z/ i F/ 7 INVENTOR.

we; a

United States Patent 2,981,114 nmvn SYSTEM r01: TUNING ASSEMBLY HermannE. F. C. Lingenbrink, Hilltown, Pa., assignor to Philco Corporation,Philadelphia, Pa., a corporation of vPennsylvania Filed Apr. 29, 1958,Ser. No. 731,831

1 Claim. or. 74-10) This invention relates to tuning means for broadcastreceivers, particularly for small, portable receivers such as pocketradios. It is a general object of the invention to provide an instrumentof the indicated type which can be accurately tuned by simple, manualoperations.

Ordinary tuning knobs and shafts, adapted to the dimensions of the humanhand and also to those of conventional receiver elements, are evidentlytoo large for" incorporation in such a small unit as can be carried in apocket'or held in one hand. If ordinary knobs, however,

were simply miniaturized in proportion to the size of the cabinet orbox, it would no longer be easy to adjust them accurately. Neverthelessa system of tuning elements is required, which elements must be movedrelative to fixed points, and/or relative to one another, withconsiderable accuracy, often for instance with an accuracy exceedingthat of the conventional adjustment of a small watch. a -A solution forthis dilemma between smallness of conv terimprovements form, added orindependentfeatures of the invention.

., Briefly described the new construction, as illustrated herein,includes a receiver box of such small size that it can conveniently beheld in one hand. According to one' aspect of the invention the, tuningsystem comprises relatively small wheel means-generally a pair of wheelspivoted and generally disposed within the small receiver exposed onopposite outer surfaces of the box, thereby allowing fine manual tuningby the relative small wheel means. According to another aspect oftheinvention two tuning wheels are directly interconnected by integralclutch means providing a controlled degree of relatively loose orlost-motion coupling therebetween; and the said wheels may additionallyprovide tuningtindicator means on furtherintegral portions of thewheels.

These and other features of the new construction will .be described morefully in conjunction with the drawing,

wherein: l

g [,Figur'e lis a perspective'view ofiapreferrcd embodiment hereof andFig'iire Z its side view of said embodiment. Figure 3 is an enlargedfragmentary sectional view; takenalong line 3-3 in Figure 2.- Figure 4is a partially exploded perspective view, of some of the parts shown inFigure: 3. -FigureS is a section taken along line 5--S'in Figure 3.Figure 6 is a front view of the receiver box of Figure l, partly brokenaway to show internal construction; and Figure 7 is a schematic wiringdiagram of the tuning system and of directly associated parts of the newreceiver.

As shown in Figure l, the pocket size receiver casing or box 10 has apair of peripherally serrated or knurled tuning wheels 11, 12-therein,each of which has a segment thereof projecting beyond the front surface13 of the box. A diametrically opposite segment of each wheel 11, 12projects similarly from the back surface 14 of the box, as shown inFigures 2 and 3. On each surface of the box, the so projecting portionsof said wheels are separated from one another by a narrow strip 15 ofthe corresponding wall 13 or 14, (Figures 1 and 8).

Selector wheels 11, 12, as shown in Figure 6, preferably have indicia,such as numbers, associated therewith to indicate station frequencies orthe like, and receptacle or casing 10 is shown in Figures 1 and 6 asproviding for inspection of such indicia, by an aperture 16 in a top orend portion of the casing. The receiver is also shown in Figures 1 and 2as having an on-off switch and volume control device 17 which utilizesan actuator wheel similar to wheels 11, 12; this latter wheel howeverbeing distinctively located and/ or arranged and projecting only fromone wall 13, remotely from the system of tuning wheels 11, 12. Anelectrical cord 18 connects the set to a suitable earphone 19 withholder 20.

Referring now to Figures 3, 4. and 5, each selector wheel 11, 12 hasloose or free-play coupling means 21 on one side thereof for the purposeof suitably interconnecting these wheels, while having rotary slidablecondenser means 22, 23 on the other side thereof. The mechanicalconstruction of both condenser means 22, 23 may be substantially thesame and only one of them has been shown in exploded form in Figure 4.

Each condenser includes a first segment carrier 24 of insulatingmaterial, carrying a conductive segment 25. A

, central conductive pin 26 is electrically connected to this box, eachwheel having tunable circuit means connected i therewith and having apairof wheel rim or segment areas segment and is mechanically connected,by a square end portion as shown, with segment carrier 24 and also withwheel 11 or 12, see Figure 3. Each condenser also includes a thindi-electric wafer 27 of suitable ceramic or .the like, which as shown inFigure 4 has a central aperture 28 for pin 26 and a conductive segment29 suitably spaced from aperture 28. A resilient washer 30 is providedwith .a similar central aperture 31 and with an eccentric aperresilientwasher, dielectric wafer and segment carrier 34,

' v30, 27 and 24 assembled. The assembly is secured to a wheel 11 or 12by press fitting segment carrier 24 intothe wheel; and due to thepivoting of elements 27, 30 and 34 onpin 26 the segments 25, 29 can berotated relative to one another, by rotating for instance wheel 12relative wafer of the second condenser 23, which is mechanically of thesame construction,while having independent electrical terminals 38, 39.

The loose coupling mechanism 21 interconnecting the two condensers 22,23 is best illustratedin Figure 5 in conjunction with Figure 4. It willbe seen that selector -Wheel-11 has jaw means 40, 41 integrally formedthereon opposite condenser 22, and wheel 12 has similar-jaws 42,"

as to leave as many gaps 44 in coupling 21 as there are jaws; and thearrangement is desirably such that the several gaps have approximatelyuniform width. This is conveniently; achievediby. using wheels 11, 120isubstantially identical construction, each wheel having twodiametrically opposite, arcuate jawsand each jaw covering for-instanceabout 85 degrees of a complete circle.

Referring now to Figurefi'it will be seen that the loose couplingmechanism 21 and the associated condenser devices 22, 23 are disposed inan upper portion of the box 10. The bearing plate 34 of each tuningwheel 11, 12 is advantageously supported by a pair of holder members 45,46;rigid with casing and disposed within the same; one such member 46can also be seen on each side of Figure 3. These holders desirablycomprise channel members rigid with wall 13 and/or 14 and frictionallyengaging edgeuportions of bearing plates 34. These latter platesdesirably taper toward one end, as indicated in Figure 4, athusfacilitating insertion in holders 45, 46. No accurate :pivoting ofwheels 11, 12 and associated parts is required,

.48; said panel having connecting means 49, 50, etc. for

condenser terminals 35, 38, etc. The panel is also provided withassociated circuit elements which are shown in Figures 6 and 7 and whichcomprise a first transformer or antenna unit 51; amplifier transformers52, 53; a detector diode 54; amplifying transistors 55, 56; andassociated circuit elements which require no detailed discussion herein.Suitable batteries 57 are used as a power source.

In order to operate the new device, the user of course starts byapplying earphone 19 and by turning switch and volume control member 17to on and to suitable volume. He then manipulates wheels 11 and 12 forthe tuning in of a desired broadcast. For such manipulation the usercanconveniently grasp the entire receptacle 10 in one hand and he mayinitially place the tips of forefinger and thumb of the same hand, onthe exposed portions of one wheel 11 or 12, in the manner shown inFigure 2, although he may, if preferred, use two fingers of the otherhand for this purpose. In either case the operation is very convenient,as the actual size of the unit is generally smaller thanthat of Figure3; and at the same time the operation is accurate, as the two-sidedgripping of each wheel, provided in this way, allows very gradual,minute shifting, particularly-by virtue of the simultaneous abutment ofeach operating finger tip against the surface of receptacle 10. I

As indicated by Figure 6, anysubstantialrotation of one tuning wheel 11or 12, provided in this way, causes rotation of the other tuning wheel,which however remains free for adjustment relative to said one wheel,.by

There may follow a correction of the disturbance of elements 51, 55,caused by the fine matching of elements 55, 56. About two to four suchconsecutive movements of the condensers are generally required foradequately sharp tuning of a pocket radio; it being generally preferredfirst to move the, two condensers conjointly, into the range of highvolume'output, and then to adjust them relative to. one another withinsaid range,

Some of these consecutive movements of the two condensers and wheels,mainly their adjusting movements relative to one another, involve veryslight, delicate and accurate rotations of wheel 11 and/or 12; and suchminute and precise motion is most readily achieved by the constructionof the receiver casing, exposing two oppovirtue of the loose couplingbetween these wheels. The

loose coupling is indicated in the circuit diagram of Figure 7 by brokenline 21 It will be understood from the latter diagram that init1al,progressive, unidirectional, rotation of one tuning condenser,22 or 23,whichresults ingenerally similar rotation of the other tuningcondenser,matches the primary or antennacoil of transformer 51 to the input ofamplifier device 55 and,-by loosecoupling 21, 'partly matches the outputof amplifier deviceSS to the input of the second amplifier device 56,thereby providing a first maximum volume of output in. earphone 19. Afurther increasein such output can then be obtained by progressively,unidirectionally moving only the other condenser to a slight extent, asis allowed by the loose mechanical coupling; this improves the'matchingof elements 55, 56,

those ofv the other.

site segment areas of each'tuning wheel. Displacements of the twowheels, relative to one another, can be detectcd and/ or effected bythis arrangement with considerably. greater accuracy than is availablewhen conventional tuningwheel designs and'arrangements are used on thesmallrscale which is here involved. The user of the new device can,.a sindicated by Figure 2, span the front and back walls of cabinet 10.between the thumb and a finger of one hand andcan thereby frictionally.engage any of the projecting segments of wheels 11 and 12. The width ofthe wheel-separating strip 15 (Figure l) is, as shown, smaller than thewidth of a thumb or other finger. Thus the. user can shift the tips ofthe fingers of the hand holding the cabinet from the segments of onewheel to The manual-adjustment, as already explained can be. carried outwith great accuracy as well as;convenience, by virtue of the wheelsegment arrangement .as: described. It can often be performed in merelya second or two.

Although only a single embodiment of the invention has beendescribed, itshould be understood that the details thereof are not to be construed aslimitative of the invention, except insofar as is consistent with thescope of the following claim;

I claim:

Ina pocket broadcast receiverz an enclosure which has front and rear.walls, so closely spaced that one hand can-spanboth of said walls; areceiver set in said enclosure; a tuning device comprising a pair offriction wheels, each being rigid and coaxial with one circuit tunerelement which forms part of the receiver set, said wheels being coaxialone with the other, both being pivoted in said enclosure, .each'h'avingasegrnental portion projecting throughsaid front wall and a segmentalportion projectingthrough said rear wall, the segmental portionsprojecting through each of said walls being spaced apart notsubstantially morewidely than the widthof a finger; and acoupling;comprising jaw means on each of the two wheels, within: said enclosure;each ofsaid jaw means being rigidly peripherally formed on one of saidwheels and-beingadapted toengage and rotate the jaw means of; theotherwheel, subjectto lost rotary motion, so that conjoint as well asrelative rotation of said pair of tuner elementscanbe effected by eachof two fingers of said one hand. 6t).v

' References iCited inthe file of this patent UNITED STATES PATENTSVreeland Mar. 11, 1930 1,914,018 Hollerith June 1 3, 1933 1,934,524Conrad 'N0v. 7, 1933 2,510,757 i ,J ne6, 0

4 FOREIGN-PATENTS LO-15,506 Germany Sept. 12, 1957 THE RE E E Radio-it.Television News, January 1955, A New Pocket Radio, page :54.- t

